CD38 and head and neck cancer: On TIMER database, compared with the adjacent normal tissues, CD38 mRNA was significantly upregulated in cervical and endocervical cancers (CESCs), colon adenocarcinoma (COAD), esophageal carcinoma (ESCA), head and neck cancer (HNSC) and kidney renal clear cell carcinoma (KIRC) and was significantly downregulated in kidney chromophobe (KICH) (Figure 1A).